week 2 Flashcards
homeostasis
the maintenance of relatively stable internal conditions despite continuous changes in environment
receptor
responds to stimuli
-first component
-monitor environment
-responds to stimuli
-sends info to control center(sweat glands are effectors)
variable
things that can change in the body..IE. blood sugar, body temp, blood volume, blood pressure.
control center
determines set point
at which variable is maintained
-determines appropriate response
-information from the control center flow to the effector
stimulus
anything that changes a variable
effector
makes change
-response either reduces stimulus(negative feedback)or enhances stimulus(positive feedback)
if you are cold, it warms us up./ too hot it cools us off
stimulus-sensor
control-effector
the structure of the plasma membrane consists of
consists of lipids that form a flexible lipid bilayer
structures in the membranes help to hold cells together through…
cell junctions
lipid bilayer consists of
mostly phospholipids
–polar heads
–non-polar tails
glycolipids
cholesterol
the extracellular surface of the membrane contains CARBOHYDRATES that attach to proteins or lipids known as …
glycoproteins and glycolipids=glycocalyx
-they serve as biological markers for the body’s cells to prevent the immune system from attacking the host
membrane proteins allow..
cell communication with environment
2 types; integral and peripheral
integral protein
firmly inserted into the membrane
-have both hydrophobic and hydrophilic regions-function as transport proteins, enzymes, or receptors
peripheral proteins
loosely attached to integral proteins OR ANCHORED TO MEMBRANES
-function as enzymes, motor proteins and cell connections
a receptor protein is..
binds to chemical messenger such as hormones sent by other cells
tonicity
the ability of a solution to change the shape or tone of cells by altering the cell’s internal water volume
isotonic solution
has same osmolarity as inside the cell, so volume remains unchanged
hypertonic
has higher osmolarity than inside the cell, so water flows out of the cell, resulting in cell shrinking(crenation)
hypotonic
has lower osmolarity than inside the cell, so water flows into cell, resulting in cell swelling (lysing)
enzyme..
breaks down products
channel protein is
constantly open and allows solutes to pass into and out of the cell
gated channel
a gate that opens and closes to allow solutes through only at certain times
cell identity marker
a glycoprotein acting as a cell identity marker
cell adhesion molecules(CAM)
binds cells to other cells
cell junctions
most cells are bound together to form tissues and organs .. the 4 ways cells can be bound to each other are..
tight junctions
demosomes
gap junctions
adherens
tight junctions
almost impermeable junction (GI)
adherens junctions
stabilize and initate
gap junctions
form tunnels that allow small molecules to pass from cell to cell (cardiac and smooth muscles)
desmosomes
prevent cells from tearing under tension (found in skin)cardiac too
intracellular fluid(ICF)
fluid inside of cells
K+, Mg+, PO43
extracellular fluid (ECF)
fluid outside of cells(includes the fluid of blood)
Na+, Cl-. Ca2, HCO3
plasma membrane is…
selectively permeable. Allows small, nonpolar molecules to easily pass through
2 essential ways substances cross plasma membrane
passive transport=no energy is required
-Active transport=energy (ATP) is required
3 types of passive transport are…
-simple diffusion
-facilitated diffusion
-osmosis
all types of passive diffusion have movement from..
areas of higher concentration to areas of lower concentration–moving down a concentration gradient
simple diffusion
lipid soluble and nonpolar molecules can passively diffuse through the plasma membrane(oxygen, carbon dioxide, small amounts of water, fatty acids
facilitated diffusion
larger or polar molecules can cross membranes but only with assistance of carrier molecules
certain hydrophobic molecules (glucose, ions) are transported passively down their concentration gradient by..
-carrier mediated facilitated diffusion
-channel-mediated facilitated diffusion
channel mediated diffusion
channels transport molecules such as…
ions or water down their concentration gradient.
2 types:
-leakage (always open)
-gated(controlled by chemical or electrical signals)
water channels are called…
aquaporins
carrier mediated diffusion
carriers transport molecules that…
are too large for membrane channels
-the binding of the molecule changes the shape of the protein
osmosis
the movement of water across a semi permeable membrane from an area of low solute to and area of high solute concentration
water diffuses across plasma membranes through..
lipid bilayers and water channels called aquaporins
this flow occurs any time there is a difference in the two sides of the membrane
osmolarity is..
the measure of the concentration of the total number of solute particles in solvent inside and outside of cell
water moves by osmosis from areas of
low solute(high water) to high solute(low water) concentration
equilibrium means…
same concentration of solutes and water molecules on both sides
movement will occur until equilibrium is met
movement of water involves pressures called
hydrostatic and oncotic pressure
hydrostatic pressure is…
outward pressure caused by fluid leaving cell
oncotic pressure is…
inward pressure due to tendency of water to be “pulled” into a cell
hypo
low
natri-natrium
sodium
emia
presence in blood
hyperatremia
salt poisoning, too much salt in the blood and body fluid due to dehydration or water loss.
causes excessive thirst, tachycardia, muscle spasms, or nervous dysfunction
-cells will shrivel (crenation)
sodium determines the osmolarity…
wherever sodium is going, water is going
hyponatremia is caused by…
kidney damage, heart failure, diuretics, overconsumption of fluids.
hyponatremia causes an osmotic shift leading to…
cellular swelling, higher concentration of solutes inside of cell due to diluted ECF fluid
Patients with hyponatremia develop severe…
neurological symptoms such as lethargy, seizures and maybe coma
two types of active transport..
Primary- required energy comes directly from ATP hydrolysis
-Secondary-required energy is obtained indirectly from ionic gradients created by primary active transport
two major active transport processes
-both require you to move solutes across a plasma membrane
for three reasons..
and solutes are being moved against their concentration gradient
active transport
vesicular transport
1.solute is too large
2.solute is not lipid soluble
3.solute is not able to move down concentration gradient
energy from hydrolysis of ATP causes …
change in shape of transport protein
in primary active transport, shape change causes…
solutees(ions) bound to protein to be pumped across membrane
in primary active transport, the sodium/potassium pump is…
-the most studied pump
-basically an enzyme called Na+ K+ ATPase that pumps sodium out of the cell and potassium back into the cell
-located in all plasma membranes, especially excitable cells like nerves and muscles
secondary transport depends on..
ion gradient created by primary active transport system
-energy stored in gradients is used indirectly to drive transport of other solutes
some sugars, amino acids and ions are usually transported into cells via…
secondary active transport
The ATP driven Na+ K+ pump stores energy by creating a steep concentration gradient for Na+ entry into the cell . this is called….
Primary active transport
as Na+ diffuses back across the membrane through a membrane cotransporter protein, it drives glucose against its concentration gradient into the cell. this is called…
secondary active transport
endocytosis involves formation of…
vesicles
it can fuse with lysosome once inside cell or undergo transcytosis
PINOCYTOSIS
CELLULAR DRINKING
Plasma membran infolds, bringing extracellular fluid and dissolved solutes inside cell.
the cell ‘gulps” a drop of extracellular fluid containing solutes into tiny vesicles. no receptors are used so the process is nonspecific
main way in which nutrients absorb in small intestine
recepetor-mediated endocytosis
a type of transcytosis.
Examples: enzymes, low density lipoproteins(LDL), insulin, iron, and viruses
exocytosis
contents in side the cell are moving out.
How endocrine glands secrete their hormones into the blood
